Thread-treating apparatus



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THREAD-TREATING APPARATUS Original Filed Dec. 30, 1948 July 3, 1951 4Sheets-Sheet 2 l union? Hwa? 4/ @n RNEY July 3, 195 f A. cREsswELl..2,558,734

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Patented July 3, 195.1

THREAD -TREATING APPARATUS- v Arthur Cresswell. Stamford, Conn.,assignor to American Cyanamid Company, New York, N. Y., a corporation ofMaine Original application December 30, 1948, Serial No. 4 68,370.Divided and this application February 28, 1950, Serial No. 146,880

4 Claims.

This application is a division of my copending application Serial No.68,370, filed December 30. 1948, and now abandoned. The claims of saidapplication Serial No. 68,370, which now appear in my copendingapplication Serial No. 73,078, filed January 27, 1949, as acontinuation-in-part of said application Serial No. 68,370, are directedto a method for the preparation of synthetic bers from polymers andcopolymers of acrylonitrile,

and more particularly to certain new and useful improvements in a methodof producing fibers (including both monolaments and multilaments) from asoluble, thermoplastic product of polymerization of'a polymerizable masscomprising mainly acrylonitrile. The claims of the present applicationare directed to a portion of the apparatus, more particularly apparatusembodying a trough of a new and novel construction which is shown invarious figures of the drawing accompanying the said application SerialNo. 68,370, and described in the specification thereof, but not claimedtherein or in the aforesaid application Serial No. 73,078.

Various methods of producing filaments, films and other shaped articlesfrom acrylonitrile (polymeric acrylonitrile) and from copolymers orinterpolymers of a major proportion of acrylonitrile and a minorproportion of another monomer or monomers 'heretofore have beensuggested. For example, in Rein U. S. Patent No. 2,117,210 it isproposed that polyacrylonitrile be dissolved in a quaternary ammoniumcompound such as benzyl pyridinium chloride, and that the resultingsolution be employed in making lms, threads and other shaped bodiestherefrom. Also, in Rein U. S. Patent No. 2,140,921 it is proposed thatvarious polyvinyl compounds including polyacrylonitrile and copolymersof acrylonitrile with another vinyl compound be dissolved inconcentrated aqueous solutions of inorganic (metallic) salts, e. g., thechlorides, bromides, iodides, thiocyanates, perchlorates and nitrates,and that the resulting solutions be used `in the manufacture of threads,films, etc. Various organic solvent solutions of polyacrylonitrile andcopolymers of at least 85% 'by weight of acrylonitrile with anothermonomer are disclosed in U. S. Patents 2,404,713- 728, and also the useof such solutions in forming films, filaments, etc., therefrom. In mostof these latter patents the aforementioned Rein patents are referred to,as well as the difiiculties eny countered when eiort was made to produceuseful laments and other shaped articles from polyacrylonitrilesolutions of the kind proposed by Rein.

The invention disclosed and claimed in my copending application SerialNo. 772,200, filed Sptember 4, 1947, is based on my discovery thatuseful lms, laments, threads and other shaped articles, which arecapableof being dyed, can be produced from acrylonitrile polymerizationproducts of the kind described broadly in the first paragraph of thisspecification, and more specifically in the aforementioned patents aswell as hereinafter, by precipitating or coagulating the polymerizationproduct in approximately its desired shape from a water-coagulablesolution thereof (e. g., concentrated aqueous salt solutions of the kinddisclosed by Rein in his Patent No. 2,140,921), the precipitation beingeiected by contacting the said solution with a cold liquid coagulantcomprising water, more particularly such a coagulant which is at atemperature not substantially exceeding |l0 C. This coagulant is anon-solvent for the polymerization product but will dissolve the solventin which the said product is dissolved. Surprisingly it was found thatby keeping the temperature of the aqueous coagulating bath at .or below-1-10 C., e. g. within the range of 15 C. to +10 C. and preferably atfrom about 15 C. to about +5 C., the precipitated gels in general areclear or substantially clear, tough, ductile and, in filament, thread orother form, can be stretched to orient the molecules, thereby increasingthe cohesiveness, tensile strength, toughness, resilience and otherwiseimorder of 20 to 50 C. or higher, the precipitated gels in general arehazy or opaque, weak, friable, have little or no toughness or ductilityand are notadapted for stretching to orient the molecules and therebyimprove the properties of the dried material.

The invention disclosed and claimed in my aforementioned copendingapplication Serial No. 772,200 is based on my further discovery that theshaped, precipitated gels, e, g., extruded, waterswollen monoiilamentsand multilaments, which may be collectively designated as yarns orfibers, and which have been formed in al cold liquid coagulantcomprising water at a low temperature of the order of that mentioned inthe preceding paragraph, can be materially improved in properties bysubjecting the precipitated material in wet, swollen state to tension,as bystretching, in contact with moisture or water and at an elevatedtemperature, specifically at a temperature within the range of about C.to about 110 C.

Advantageously water at 70 C. to 100 C., preferably at 90 C. to 100 C.,is the fluid medium with which the gelled or precipitated fiber or otherproduct is contacted during the stretching operation, but iftemperaturesabove 100- C., e. g., 110 C., are desirable, then anatmosphere of saturated steam may be employed. For optimum resultsduring stretching it is important that moisture or water be present. Bythus wet stretching the precipitated product, more particularly to anextent at least twice its original length (that is, at least 100%) andpreferably from 3 to 20 or 30 or more times its original length, themolecules are oriented along the ber axis and a product having increasedtensilev `both continuously spun, stretched and dried whereby a fiber orthread is obtained more quickly and with a minimum of handling'so thatthe product is more uniform and is less subject to damage duringprocessing than-for example, a package-spun ber or thread.

4 particularly a thermoplastic copolymer, are compounds containing asingle`CH2-C grouping. for instance the vinyl esters and especially thevinyl esters of saturated aliphatic monocarboxylic acids, e. g., vinylacetate, vinyl propionate, vinyl butyrate, etc.; acrylic andv alkacrylicacids (e. g., methacrylic, ethacrylic, etc.) and esters f and amides ofsuch acids (e. g., methyl, ethyl,

propyl, butyl, etc., acrylates and methacrylates, acrylamide,methacrylamide, N-methyl, -ethyl, -propy1, -butyl, etc., acrylamides andmethacrylamides, etc); methacrylonitrile, ethacrylonitrile and otherhydrocarbon-substituted acrylonitriles; and numerous other vinyl,acrylic and other compounds which are copolymerizable with acrylonitrileto yield thermoplastic copolymers. Alkyl esters of alpha,beta-unsaturated polycarboxylic acids also may be copolymerized withacrylonitrile to form copolymers which are useful in practicing thepresent invention, e. g., the

dimethyl, y-ethyl, -propyl, butyl, etc, esters of maleic, fumaric,citraconic, etc., acids.

A suitable method of polymerizing the, monomeric acrylonitrile ormixture of monomers is in anraqueous emulsionusing a suitablepolymeri'zation catalyst, e. g.. ammonium persulfate. Otherpolymerization methods, however, also may y be employed, e. g., methodsysuch as those de- The novel features which are characteristic of thepresent invention are set forth in the appended claims. The manner inwhich the apparatus in constructed and used will best be understood byreference to the following more detailed description when considered inconnection with the accompanying drawing in which Fig. 1 is adiagrammatic view of one portion and Figs. 2, 3'and 4 are diagrammaticviews, shown in perspective, of other portions of apparatus that may beused, and illustrative thereof; Fig. 5 is a view in perspective of apart of the apparatus shown in Fig. 1; Fig. 6 is a transverse sectionalview along the line 6-6 of the apparatus shown in Fig. 5; Fig. 7 is afragmentary sectional view taken along the line 1--1 of Fig. 6; Fig. 8is a somewhat diagrammatic side view, partly in section, of another andpreferred form of apparatus which may be used; and Fig. 9 is a somewhatdiagrammatic front View, partly broken away, of the apparatusillustrated in Fig. 8.

' In practice, a polymer or copolymer of acrylonitrile is rst preparedin accordance with methods now well known to those skilled in the art.In the preparation of copolymers a mixture of monomers comprisingmainly, that is, a preponderant proportion by weight of, acrylonitrileis employed, and preferably the acrylonitrile constitutes at least aboutby weight of the mixture of monomers. If less than about 50% by weightof acrylonitrile be present in the mixture of monomers, the fulladvantages are not obtained when processing the resulting copolymer inaccordance with the invention claimed in the parent application. Themonomeric mixture therefore should contain substantially more thanscribed in Bauer et al. U. S. Patent No. 2,160,054. The polymeric orcopolymeric acrylonitrile may be of any suitable molecular weight, butordinarily it will be within the range of 15,000 to 300,0000 or higher,as calculated from viscosity measurements by the Staudinger equation(reference: U. S. Patent No. 2,404,713).

The polymeric or copolymeric acrylonitrile is then dissolved in asolvent from which the polymer (or copolymer) is precipitated orcoagulated when the solution is brought into contact (e. g., immediatelyafter extrusion) with a liquid coagulant comprising water, moreparticularly water which is at a temperature not exceeding substantially+10 C., preferably at or below +5"y trates, which salts are disclosed inthe aforementioned Rein Patent No. 2,140,921 and the concentratedaqueous solutions of which are the preferred solvents for theacrylonitrile polymerization products, more particularly such a productcontaining in the molecules thereof an average of at least about byWeight of combined acrylonitrile, in carrying out my process. Saturatedor nearly saturated aqueous solutions of such salts in' some cases maybe used. More specific examples of such water-soluble inorganic saltsare zinc chloride, calcium chloride, lithium bromide, cadmium bromide,cadmium iodide, sodium thiocyanate, zinc thiocyanate, aluminumperchlorate, calicum perchlorate, calcium nitrate, zinc nitrate, etc.Other examples of suitable solvents are concentrated aqueous solutionsof guanidine thio'cyanate,` the mono.- (lower alkyl) -substitutedguanidine thiocyanates and the symmetrical and `unsymmetrical di-(loweralkyl) -substituted guanidine thiocyanates. These solutions containingdissolved polymeric or copolymeric acrylonitrile are more fullydescribed and are specifically claimed in my copending applicationSerial No. 772,201, filed September 4, 1947, now Patent No. 2,533,224,issued December 12, 1950.- I prefer to use a concentrated aqueoussolution of a thiocyanate as the solvent for the acrylonitrilepolymerization product.

With reference to the accompanying drawing and more particularly to Fig.1 thereof, a watercoagulable solution of the polymeric or copolymericacrylonitrile, which has been filtered (if necessary) and de-aerated, ispassed under pressure from a supply reservoir (not shown) through theconduit I (Figs. 1 and 8) into a spinneret coupling or heading I2, whichpreferably is designed so that the solution can be heated, e. g., byelectrical, hot water, steam or other means. prior to extrusion throughthe spinneret-l I4. A suitable design of a spinneret coupling, which isheated by electrical means, is shown in Fig. 2 of the drawingaccompanying my aforementioned copending application Serial No. 772,200.The

device there illustrated, and portions of which will be described hereinwith reference to Fig. '1 of the present drawing, comprises a malecoupling I6 in which is annularly spaced an electrically heatedcartridge provided with lead-in wires I8. This cartridge advantageouslymay be tted in the male coupling IB by means of a liquid-tight plug. Theelectrically heated cartridge is so positioned as to project beyond thelower end of the male coupling I6 and into the cup of the spinneret I4,which is attached by means of a female coupling 20. The solution beingcharged through conduit I0 passes annularly between the outer wall ofthe cartridge and the inner wall of the male coupling I6 and thence intothe spinneret I4. Since the electrically heated cartridge projects intothe cup of the spinneret, the solution is maintained at an elevatedtemperature prior to extrusion. The temperature of the solution may bevaried as desired or as conditions may require, but ordinarily will bewithin the range of 60 C. to 100 C. By heating the solution immediatelyprior to extrusion, its viscosity is materially reduced and asubstantial reduction in operating pressure is eiected. Furthermore, byincreasing the fluidity of the solution at the point of extrusion, thewater-swollen or gelled laments can be pulled from the spinneret at agreater speed, thereby increasing the amount of ber or yarn that can beproduced from a particular unit.

The spinneret coupling I2 may be held by suitable means (not shown)above the cold aqueous coagulating or precipitating bath 22 in vessel 24at any convenient angle. For example, the spinneret coupling may bepositioned at less than a 90 angle to the surface of the aqueouscoagulating bath 22 as shown in Fig. 1 of the drawing accompanying thepresent application or at approximately a 90 angle to the surface of thesaid bath as shown in Fig. 1 of the drawing of my aforementionedcopending application Serial No. 772,200. The coupling preferably ispositioned so thatonly the face of the spinneret contacts thecoagulating bath.

As the solution is forced under pressure through the openings in thespinneret, it coagulates or precipitates in the form of solid,water-swollen or gelled laments or ber 26 upon entering the coagulatingbath 22,*which is maintained at a temperature not exceedingsubstantially +10 C.

by any suitable means. For example, water may be refrigerated or cooledto the desired low temperature and circulated through the vessel 24,

being introduced through the conduit 28 and withdrawn through theconduit 30. Alternatively, and as shown in Fig. 1 of the drawingaccompanying my aforementioned copending application Serial No. 772,200,Acooling coils through which is circulated a liquid coolant, e. g.. arefrigerated brine solution, may be employed to maintain the bath 22 atthe desired low temperature. It will be understood, of course, thatvarious other means may be used to keep the bath 22 at or below -|-10 C.For instance, instead of employing means such as mentioned above, I mayadd ice alone to the bath, or a mixture of ice and sodium chloride orother salt, or ice and methyl or ethyl alcohol, or other suitabletemperature depressants or mixtures thereof in order to reduce lthe bathof liquid coagulant comprising mainly water to the desired lowtemperature.

The coagulated ber in gel state is led through the bath 22, whichpreferably is of the circulating type, by any suitable means. Duringpassage of the ber through the bath it is washed substantially free ofsalt.

'I'he gelled ber may be led through the bath 22 merely with the aid of aguide roll or sheave 32 to facilitate the passage of the ber through thecoagulating bath, as is shown in Fig. 1 of the drawing accompanying myaforementioned copending application Serial No. 772,200. Advantageously,however, the gelled ber is led through the bath 22 with the aid of asubmerged, powerdriven godet 3d and multi-groove roll 36. For instance,the gelled ber may be led through the bath 22 and out of it, as is shownin Figs. 1, 8 and 9, with the aid of guide roll 32, power-driven godet34 and multi-groove roll 36. The gelled ber is wrapped several timesbetween the godet 34 and the multi-groove roll 36. This arrangementpermits a long bath travel by multiple winds of synthetic ber, withoutcausing excessive tension on the ber, such as may occur when a pair ofmulti-groove rollers alone is used in leading the ber through the bath.

It is important that the coagulating bath 22 be at a temperature notexceeding substantially +10 C., and preferably at or below +5 C., e. g..10 C. to 0 C. or l1 or |2 C. Temperatures below -15 C., e. g., 20 C. orlower, may be employed if desired, but such "temperatures are morecostly to secure and maintain, and no particular advantages appear toaccrue therefrom. By the use of a low-temperature, aqueous coagulatingbath as herein described, the shaped, coagulated or precipitatedmaterial, more particularly an extruded, water-swollen or gelled ber orthread, is clear (transparent) or substantially clear, cohesive, hasconsiderable elasticity and toughness, and is capable of being oriented,e. g., by stretching. In marked contrast, when the aqueous coagulatingbath is substantially above +10 C., e. g., +20 C. or |25 C. or higher,vthe resulting ber or thread usually either is'opaque or showsconsiderable haze, is spongy and has little or no mechanical strength.Furthermore, it is either unstretchable or has a low order ofstretchability, yielding o'n drying a brittle ber or thread which cannotbe used for textile purposes.

Furthermore, when multifilaments are produced with the aid of alow-temperature` coagulating bath as herein described, the individualwater-swollen or gelled laments show no tendency to stick together. Thiswas quite surprising andunexpected, as was also the fact that the factthat these discoveries are directly contrary to the prior art teachings.Forexample, .in Patent No.. 2,404,716 and in numerous other patents itis stated that it has been found substantially impossible to use thesolutions proposed in Rein Patent No. 2,140,921 in the production ofAyarns and films, and that their extrusion into coagulating baths,including such non-solvents for polyacrylonitrile as water, dilute acidsolutions, dilute salt solutions, etc., results in the formation ofsh'apedarticles that contain large amounts of the inorganic saltcomponent of the solvent. The prior artalso teaches'that these salts aredistributed throughout 'the structure, that the latter possesses poorphysical properties and that the removal of these salts, when possible,results in the formation of a porous, spongy, weak,`undesirablefstructure that is very brittle and completely unsuited foruse as a yarn or lm. The prior art further teaches that when an attemptis made to form a multiiilament yarn by extruding an aqueous sodiumsulfocyanide (sodium thiocyanate) polyacrylonitrile composition into adilute acid bath. the individual filaments that are obtained sticktogether to form an essentially monoiilament structure which isextremely 'brittle and cannot be bent or worked without vleaving thecoagulating bath in order to orient the molecules and thereby toincrease the tensile strength and otherwise to improve the properties ofthe spun material. Orientation is preferably effected by stretching thefiber, while still in its water-swollen or gel state, in the presence ofmoisture and at a temperature within the range of about 70 C'. to about110 C., more particularly at a temperature of about 90 C. to about 100C. This stretching may be effected, for exf ample, in the mannerillustrated in Fig. 1 of my aforementioned copending application SerialNo. 772,200 or, preferably,as illustrated in Fig. 1 of the drawingaccompanying the instant application.

With reference to Fig. 1 of the drawing of the present application, theber 2G after leaving the aqueous coagulating bath'22 passes over therevolving wheel or godet 38 and the auxiliary roller 39, being wrappedone or more (e. g., two or three) times about each, into the hot aqueousliquid medium 40, e. g., hot water, contained in the stretch trough 42,and thence over the godet 44 and the auxiliary roller 45, about each-ofwhich the iiber also is wrapped one or more (e. g., two or three) times.The peripheral speed of the godet 38 may be slightly greater than thatof the godet 34. The godet 44 is caused to revolveat a peripheral speedgreater than that of l ly, but in all cases should be suiiicient tocause at least appreciable orientation of the molecules and animprovement in the properties of the fiber undergoing treatment. Theamount of tension to which the iiber is subjected obviously should -notbe so great as to cause the ber to break.

' Depending, for example, upon the `type of matethe godet 38; in otherwords. the surface speed of the godet 44 is such that the ratio ofIspeeds of godets 38 and 44 is. proportional to the desired ber in a gelstate may be applied by any suitable rial being stretched or elongatedand the particular properties desired in the finished product, theamount of stretch may Vary, for instance, from preferably from 200 or300%, up to 4000% or more of the original length of the ber.

The stretch trough 42 illustrates one suitable form of apparatus whichmay be used in the stretching operation. A perspective view of thistrough is shown in Fig. 5; a transverse sectional view, in Fig. 6; whilea fragmentary, sectional view taken along the line 1-1 of Fig. 6 isshown in Fig. 7. This trough is positioned between the godets 38 and 44so that the ber 26, which is tangent to the tops of the godets, isslightly above (e. g., about 1/8 inch above) the bottom of the V-shap'edtrough portion 54 as it rpasses through the hot aqueous liquid mediumcontained in the trough 42.` The ber 26 `enters the stretch trough 42slightly above the bottom portion of the U of the U-shaped slot 56 inthe end wall 58 of the trough. The hot aqueous liquid medium in whichthe fiber is stretched is preferably circulated through the trough 42,entering the trough.

through the conduit so, is forced through the" openings 66, therebymildly agitating the hot aqueous liquid in the trough. The liquid medium40 iiows along the `V-sh'aped trough portion 54 f into the collectingreservoirs 68 and 'l0 located at each end of the stretch trough 42, fromwhich reservoirs lit then passes through the conduits 52 and 64 to asupplyreservoir (not shown).v

The hot aqueous liquid medium 40 which is circulated through the trough42 may be heated.

by any suitable means (not shown) to the desired temperature. Forexample, the water or other aqueous liquid medium employed may beehcatedelectrically, or by gas, steam or other'means, in a suitable heatingunit havinga supply reservoir and connecting conduits to and from thelstretch trough 42` for circulation of the hot aqueous liquid mediumbetweenthe supply reservoir and the stretch trough. To conserve heat andin order better to maintain the temperature of the aqueous liquid in thestretch trough, it is usually desirable to insulate the trough withvsuitable heat-insulation, e. g., glass fibers, asbestos, cork, etc., inboard, sheet, tape or other form in which these materials are availablefor use as heat insulation. A suitable cover (not shown), which may behinged or which merely may fit loosely over the top of the trough and isremovable Y blown neats-foot oil, sperm oil, olive oil, teaseedtherefrom, also advantageously may be provided in order to reduce heatlosses and to provide a better control of the temperature of the hotaqueous liquid in the stretch trough. Such a cover likewise ispreferably insulatedvwith a. suitable insulating material such as one oranother of those mentioned above by way of illustration. The cover israised or removed (ity detachable from the trough; when threading-up"the apparatus, and is closed or put back into place after the thread hasbeen positioned in the stretch trough. v

Among the advantages of using a stretch trough of the kind describedabove, and shown in Figs. 5, 6 and? and in a portionvof Fig. 1, may bementioned the following:

The thread, during its stretching operation, may be subject tomechanical damage. i. esulament breakage, abrasion, etc., if it comes infrictional contact with-such devices as hooks. rollers or sheaves, whichconventionally are used to submerge a thread in a bath. Theabove-described device avoids this defect by having no frictionalcontact on the thread during this critical operation. Another advantageaccrues by reasonof the slight lift imparted to the thread by themultitude of small jets of water under the thread. thereby preventingany possible sag and contact of the thread with the bottom of thetrough.

With reference to Fig. 2 of the drawing, the stretched, gelled ilber 46on the bobbn 50 is then treated with a liquid composition, moreparticularly an aqueous dispersion, containing an antistatic vagent byplacing the bobbn supported on.

a trunnion 12 in the vessel il containing the anti-static treating orfinishing composition. The helices of gelled fiber on the bobbn aretreated throughout their length with the liquid anti-static compositionas the bobbn rotates while withdrawing the gelled fiber from the bobbinas indicated in Fig. 2. Any suitable antistatic agent may be employed.Examples of anti-static agents which may be used are the guanylurea andguanidine salts of monoaliphatic hydrocarbon esters of sulfuric acid.more particularly such salts wherein the aliphatic hydrocarbon groupingcontains from 12 to 18 carbon atoms, inclusive, e. g., guanylureaoctadecyl hydrogen sulfate, guanidine octadecyl hydrogen sulfate,guanidine oleyl hydrogen sulfate, etc. Still other examples ofanti-static agents which may be used are -alkoxypropionitriles, e. g.,octadecoxypropionitrile; reaction products of ethylene oxide and along-chain alkyl guanamine,`e. g., octadecyl guanamine; and reactionproducts of ethylene oxide and a longchain alkyl guanidine, e. g.,octadecyl guanidine.

It is not essential that the liquid treating composition, e. g., anaqueous dispersion, which is applied to the stretched, gelled ber I6contain only an anti-static agent as the sole effect agent which ispresent in the composition. In some cases, however, it may be desirableor advanageous to use an anti-static agent alone as the sole effectagent, more particularly such agents Awhich are inherently capable offunctioning both as a lubricating agent and as an anti-static agent. Inother cases it may be desirable to use the antistatic agent inconjunction with other conditioning or effect agents which are commonlyemployed in, treating synthetic fibers, more particularly bers producedfrom acrylonitrile polymerization products. Such auxiliaryvconditioningagents include mineral, vegetable and animals oils, among oil, peanutoil, soya bean oil and cottonseed oil, as

' well as the various sulfonated oils, e. g., sulfonated olive oil.Examples of other conditioning agents that may be employed inconjunction with the aforementioned guanylurea saltr or guanidine saltor other anti-static agent are wetting and dispersing agents and textilelubricants of various kinds, for disodium sulfosuccinamate, dioctylsodium sulfosuccnate, lecithin, esters of long-chain fatty acids, e.g.,v alkyl stearates, palmitates and oleates, more particularly theethyl, propyl, butyl and amyl stearates, palmitates and oleates.

After being treated with the liquid ilnishing composition containing theanti-static agent, the treated, stretched ber in gel state is ledcontinuously over the drying rolls 16, thence to a pigtail thread guide18 and iinally to a suitable twister bobbn such, for example, as thering twister whereby the dry, twisted ber or thread 82 is collected onthe bobbn 84. Instead of the ring twister shown in each of Figs. 2, 3, 4and 8, any other suitable type of twister, e. g., a cap twister, orother ber take-up device adapted to cause the ber to move over thedrying rolls 16 and to be collected on a liber or thread-storagedevicemay be employed.

The drying unit shown by way of example in Figs. 2, 3 and 4 lcomprisestwo positively driven drums or rolls 86 and 88, suitably spaced fromeach other, e. g., 6 or 8 inches or more, suspended in the same plane,and rotating at the same peripheral speed. The rolls areslightlyinclined (i. e., converge) toward each other at the delivery end therebyto advance the thread over the rolls. The degree of convergency maybevaried as desired or as conditions may require in order to advance thethread in a plurality of helices over the rolls. Either one or bothrolls may converge slightly toward each other at the delivery end, thedegree of convergence being` shown in an exaggerated manner in variousfigures of the drawing. With rolls 4 inches in diameter and 10 incheslong, satisfactory results have been obtained by having the lower rollconvergent to the upper roll, at the delivery end, by an angle of about0.6". If desired, both rolls may be tilted at a suitable angle to thehorizontal, e. g., at an angle of approximately 5 to the horizontal.

Either or both of the rolls 88 and 88'may be heated by any suitablemeans. For example, the rolls may be heated and the advancing threaddried by blowing a blast of hot air or other hot gas over the surfacesof either or both rolls. Preferably, however, either or both rolls arehollow and are internally heated so as to provide a surface temperatureon the exterior of the rolls within the vrange of about 40 C. to about200 C.,'

more particularly within the range of about 50 or 60 C. to 100 or 120 C.Thus the hollow rolls or drums may be internally heated electrically, orby steam, Ahot air or other gas, hot water or by any other suitablemeans. A simple method of internally heating either or both rolls is byradiation from electrical strip heaters positioned within the rolls,which heaters are mounted by clamping onto a support bar. The electricalconnections for the heaters may be attached through the oval-shapedhollow plate 90. Preferably both rolls are internally heated.

From the foregoing description it will be seen that the advancinghelices 92 of the treated gelled ber are dried continuously, and that aportion which latter may be mentioned blown and un- 75 ofeach helix isin contact with a heated surface,

instance N-octadecyl f application of the anti-static agent to thegelled ber prior to its passage over the heated rolls, there is noaccumulation of an electrostatic charge on the fibers during theirpassage over the rolls and, therefore, no difliculty in the continuousdrying of these particular bers of an acrylonitrile polymerizationproduct by the -particular method herein described. In the absence ofsuch a pretreatment of the wet, gelled ber with a composition comprisingan anti-static agent, it is extremely difficult, if not impossible,

to successfully dry advancing helices of a wet ber of an acrylonitrilepolymerization product due to the charge of static electricity which theber accumulates (apparently mainly as a result of friction as the berpasses over the surface of the roll), thereby causing spreading of the.laments in each helix so that successive helices may overlap and causedamage to the filaments. Furthermore, when the dry thread is deliveredfrom the drying rolls to the twisting bobbin or other collecting device,the ballooning of the laments caused` by the accumulated static chargemay cause mechanical damage to the thread when 'contacting frictionpoints such as pigtail guide 18.

The rolls 86 and 88 may be made of any suitable material such, forexample, as Monel metal,

stainless steel, aluminum, chromium-plated copper, chromium-platedsteel, anodized aluminum, dense graphite, fused quartz, glass,resin-impregnated glass ber laminate, etc. The rolls are preferably madeof a material which is a good heat conductor, that is, a material whichwillv permit the rapid transfer of heat from the interior surfaces tothe external surfaces of the roll. The rolls may be made of one basematerial, which then may be plated or otherwise covered with a smoothlayer of another material, e. g.,v

a chrome plating.

Flg. 3 illustrates another embodiment wherein the spinning solution ofpolymeric or copolymeric acrylonitrile `is continuously spun to yield awaterswollen or gelled ber 26 as has been described above with referenceto Fig. 1. This gelled ber is then stretched as it passes through a hotaqueous liquid medium, e. g., Water at atemperaturebetween about 70 C.and 100 C., more particularly at 90-100 C., contained in the stretchtrough 42. Stretching is effected with the aid of the godets 38 and 44as likewise has previously been described with reference to Fig. 1. Thestretched or oriented, gelled ber 46 is then treated with a treatingcomposition comprising an anti-static agent by continuously passing itthrough a trough $4 through which is circulated an anti-static treatingvcomposition, which may be of the kind described above with reference toFig. 2. In Fig. 3 the trough 94 is shown as being of the same design asthe stretch trough 42 (Figs. 1, 4, 5, 6 and '1), but it will beunderstood, of course, that any suitable vessel or container,'which willhold or through which can be circulated the anti-static treatingcomposition and through which the ber can be continuously passed incontact with the said composition, may be employed. The antistatictreating composition which is circulated through the trough 94 may be atany suitable temperature, e. g., within the range of about 40 C. toabout '70 C. Circulation of the anti-static composition through thetrough is effected in the same manner as has previously been describedwith reference to the circulation of water through the -stretch trough42. After being treated with the liquid nishing composition containingthe anti-static agent, the treated, stretched ber in gel state is thencontinuously dried by passing the ber over the drying rolls '|6 as hasbeen described above with reference to Fig. 2.

Fig. 4 illustrates an embodiment which differs lfrom the embodimentshown in Fig. 3 in that, instead of using separate baths for stretchingthe ber and for treating it with' a composition comprising ananti-static agent, both operations are effected by continuously passingthe gelled ber 26 through a combination stretch and anti-static treatingbath `96. During its passage through this bath the gelled ber 26 isstretched with the aid of godets 38 and 44 in contact with a liquidmedium comprising water and, also, is simultaneously treated with ananti-static agent (numerous examples of which have been givenhereinbefore), since such an agent likewise is a component of the liquidmedium. The temperature of the liquid medium constituting the combinedstretch and anti-static treating bath may be considerably varied, but isusually within the range of about 70 C. to about 100 C. The stretchedgel, which has been treated with an anti-static agent conjointly' withstretching .to orient its molecules along the ber axis, is thencontinuously dried by passing the ber over the drying rolls 'I6 as hasbeen described above with reference to Fig. 1.

Figs. 8 and 9 illustrate still another embodiment. In the embodimentthere shown the spinning solution of polymeric or copolymericacrylonitrile is continuously spun to yield a waterswollen or gelled ber26 as has been described above with reference to Fig. 1. The ber thenpasses over the guide rolls 98 and |00, and thence over the mechanicallydriven godet |02 and the auxiliary roller |04, being wrapped one or more(e. g., two or three) times about each. The peripheral speed of thegodet |02 may be slightly greater than that of the godet 34. The ber isthen carried down into the hot aqueous liquid medium 40 contained in thevessel |06, which is provided with suitable inlet and outlet conduits(not shown) for circulating the hot aqueous medium, e. g., hot water ata temperature of about '10 C. to about 100 C., preferably at 90-,l00"C., through the vessel. In the vessel |06 the ber ypasses over theroller |08 and is then carried upwardly to the cylindrical rollers I0and |2 about which it is wrapped to form a plurality of helices. Therollers I0 and I2 rotate at the same peripheral speed. The peripheralspeed of the lrollers ||0 and ||2 is greater than that of the godet |02and is adjusted so as to apply the desired stretch or elongation to theber as it passes through the hot aqueous medium 40.

The rollers I0 and I2 converge slightly in going from the feed-on end tothe delivery end, as previously has been described with reference to thedrying rolls shown in Figs. 2, 3 and 4, thereby to cause the ber toadvance in a helical path over the rollers to the delivery end. Theserollers are internally divided by insulating sections ||4 and |||i, theouter cylindrical walls of which are perforated with suitable holes,slots or openings of other shape in order to permit the rapid escape 0fheat therefrom'during operation of the appawhile sections 22 and |24 areheated.

As the stretched, gelled ber advances over the unheated sections 8 and|20 of the rollers and 2, a finishing composition containing ananti-static agent is sprayed upon the lower roller 2 from jets |26attached to supply conduit |28. As the finishing composition flows downover the roll, it contacts the wet gelledfiber and thence drips or flowsinto the basin |30 provided with conduit |32 for withdrawing theexcessfinishing composition. The finishing composition containing theanti-static agent, numerous examples of which have been given before, isusually heated prior to spraying it upon the roller, e. g., to atemperature of the order of 40 to 'I0-80 C. A f

(Instead of applying the anti-static finishing composition to anunheated section of rolls such as those shown in Figs. 8 and 9, I havefound that effective results also can be obtained by using rolls whichare internally heated and applying the anti-static composition, as byspraying, to the ber at the feed-on end of the rolls, which are soheated that the surface temperature at the feedon end is less than thetemperature at the delivery end.)

Instead of spraying only the liquid composition containing theanti-static agent upon the roller ||2 as shown, a plurality of spraysand of catch basins for collecting the surplus may be provided forspraying different liquid compositions, in

addition to such a composition containing an anti-static agent, uponthis roller. For example, a spray of water alone may be applied theretofollowed by a spray of the liquid anti-static composition; or, theapplication of the anti-static material may be preceded by a spray ofanother conditioning or effect agent such, for example, as an emulsionof a textile lubricant in the event that the particular finishingcomposition containing an anti-static agent which is employed ,islacking the same or is unable to lubricate the fiber adequately.

The wet, treated, stretched fiber continues to move in a helical pathvfrom the vunheated sectionsl ||8 and |20, over the insulating sections||4 and I6, and thence over the heated sections |22 and |24. As thehelices pass over these heated sections, the ber is continuously driedin the same i manner as previously has been described with reference toFigs. 2, 3 and 4. The heated sections |22 and |24 are heated, forexample, by the passage of steam, hot water or other hot liquid from thesupply conduit |34 through the rotary joints |36 and |38 and thence tothe linterior of the sections, the fluid medium being withdrawn from thesystem through the conduit |40.

The dried ber |42 is led from the delivery end of the roller l0 to apigtail thread guide 44 and thence to a suitable twister bobbin such,for example, as the ring twister |46 whereby the dry, twisted fiber orthread is collected on the bobbin |48.

It will be understood, of course, by those skilled in the art that thesolution of the polymeric or copolymeric acrylonitrile in the chosensolvent should be of such a concentration that a composition having aworkable viscosity is obtained. The concentration of the polymerizationproduct will depend, for example, upon the particular solvent andextrusion apparatus employed, the diameter of thev ber to be spun andthe molecular weight of the polymerization product, which usually isWithin the range of 15,000 to 300,000,

as calculated from viscosity measurements by the Staudinger equation,and advantageously is of the orderv of 35,000 or 40,000 to 140,000 or150,000. The concentration of polymer or copolymer may range, forexample, from 7 or 8% upto 18 or 20% by weight of the solution. Theviscosity of the solution, as determined by measuring the time inseconds for a Monel metal ball 1/8 inch in diameter to fall through 20cm. of the solution at 61 C., may be, for instance, from 10 to 500seconds. It has vbeen found that the best spinning solutions from thestandpoint of coagulation and optimum properties of the precipitated gelare those which contain the highest concentration of polymer and thelowest concentration of zinc chloride, sodium or calcium thiocyanate,guanidine thiocyanate or other salt ofthe kinds aforementioned, whichconcentrations are consistent with solubility and viscosity limitations.A concentration of 15% polymeric or copolymeric acrylonitrile in 50-60%sodium or calcium thiocyanate solution has been found to give verysatisfactory results. The viscosity of the solution should not be sohigh that it is diilcult to filter or to stir and deaerate prior to use.

As has -been pointed out hereinbefore and in my aforementioned copendingapplication Serial No. 772,200, the temperature of the aqueouscoagulating bath is critical in the formation of a useful, workable,polymeric or copolymeric acrylonitrile ber or other structure. When thepolymerization product is coagulated inwater at a temperaturesubstantially above +10 C., e. g., at 20 or 25 C. or higher, an opaque,weak, nonductile structure results. This structure becomes increasinglyweak and less transparent the higher the temperature of coagulationabove about +10 C. However, by coagulating in a liquid coagulantcomprising water at or below +10 C., e. g., in water at +1 to +5'J C.,or inA an alcohol-water mixture at lower temperatures, e. g., at 0 to-10 C., the coagulated product is clear or substantially clear,cohesive, tough, ductile' and capable of being oriented in itswater-swollen or gel state. Generally speaking, the clearer the gelledor coagulated material, the greater its ductility.- After coagulationand washing, the product contains at the most only a barely detectibleamount of salt from the salt solution used as a solvent and issubstantially homogeneous in structure.

In order that those skilled in the art better may understand the mode ofoperation, the following examples are given by way of illustration andnot by way of limitation. All parts and percentages'are by weight. 1

Example 1 One hundred parts of water-free acrylonitrile `was mixed with1470 parts of water in a jacketed container provided with a stirrer. Themixture was heated to 40 C., and 0.75 part of ammonium persulfate, 0.75part of sodium metabisulfide and 1.87 parts of sodium sulfate were addedthereto in the order just given. The polymerization reaction was allowedto proceed for two hours with the jacket temperature so adjusted as tokeep the temperature of the reaction mass at 40 C. The resulting slurrywas filtered. and the cake was washed by re-slurrying in water andre-fltering until a negative test for sulfate ion was obtained. Thewashed, crumbly mass of polyacrylonitrile was spread on stainless steeltrays and dried for about 16 hours at 65 C. in a circulating air oven.The dry. crumb was then ball-milledto a fine powder. A solution of 1gram of the powdered polyacrylonitrile, produced as above described, was

mixed into the cooled aqueous solution of calcium thiocyanate with rapidstirring.

The resulting slurry was transferred to a mixing unit comprising ajacketed stainless steel tank provided with a cover and a stirrer, andwas stirred therein for 48 hours at 45 C. under an atmosphere of carbondioxide in order to effect complete solution of the polyacrylonitrilevin the aqueous calcium thiocyanate. The resulting solution was filteredby forcing it. through a sand filter under 40 pounds carbon dioxidepressure. The iiltered solution was held under vacuum for several daysat C. until all of the gas bubbles had been removed. The resultinggas-free solution was then held under vacuum for an additional 18 hoursprior to use as a spinning solution. The polymer content of thesolution, as determined by casting, dryingand weighing a lm of the castsolution, was 7%. The viscosity of the solution, as' determined bymeasuring the time- `for a Monel ball, 1/8 inch in diameter and weighing0.142 gram, to fall through 20 centimeters of the solution maintained at61 C., was 208 seconds.-

The above solution was spun into iibers by extruding it through a40-ho1e spinneret with holes of 110 microns diameter into a coagulatingbath consisting of water cooled to 1-2 C. The solution was heated insidethe spinneret prior to extrusion by means of a steam-heated "finger. Thecoagulated fiber was carried back and forth through the bath by means ofa powerdriven, submerged godet position at one end oi' the bath and aset of free-running rollers at the other end. The total bath travel ofthe gelled fiber was about 144 inches.

The spun iiber was led out of the coagulating bath over several guiderollers and a driven godet through a 12-inch trough containing waterheated to 98-99 C. The fiber was stretched in this bath about 600% byleading it over a second drivenv godet, the peripheral speed of whichwas greater than that of the previous godet, and thence over a rolleronto a take-up bobbin. The take-up bobbin was provided with a. traversemotion and was vcontinuously sprayed with water to retain the fiber inthe gel state. When suicient thread had been spun the bobbin was removedand submerged in water to remove any residualcalcium thiocyanate thatmay have been present in the gelled thread.

The bobbin of wet gelled yarn was then suspended in a trough containingan aqueous dispersion of 1% of an anti-static agent, specificallyguanidine octadecyl hydrogen sulfate, and 0.5% of a' textile lubricant,more particularly butyl stearate. The dispersion was maintained at 40-50 C.

Yarn from the immersed bobbin and which had been treated with adispersion containing an Aanti-static agent was continuously led over adrying unit consisting of two, positively driven, stainless steel rolls,each of which was 4 inches in diameter and 10 inches long, and whichwere suspended in the same plane 8 inches apart and were slightlyinclined toward each other at the delivery ends thereby to advance thethread over the roll. Each roll was electrically heatedv internally soas to provide an external surface temperature of about 65-70 C., and wasrotated at a peripheral speed of about 33.8 meters per minute. The wetgelled yarn was helically wound around both rolls to form 42 loops orhelices, each having an average circumference of about 0.724 meter. Thedried yarn was then led directly from the delivery end to a ring twisterfor an insertion of 1.8

turns per inch S twist. The yarn dried satisfactorily withoutaccumulation of an electrostatic charge, and with no damage to the driedfibers or any operating difilculties during drying.

The iinished yarn had a denier of 115, contained 0.92% by weight ofthedried untreated yarn, of fi'nish, had a dry tensile strength of 4.5grams per denier, a wet tensile strength of 3.6 grams per denier, anddry and wet elongations of 14%.

Example 2 One part of methyl acrylate and 19 parts of water-freeacrylonitrile were mixed with 329 parts of water in a jacketed containerprovided with a stirrer. VThe mixture was heated with stirring to 40 C.,after which 0.3 part'of ammonium persulfate, 0.3 part of sodiummetabisulte and 0.33 part of sodium sulfate were added thereto in thisorder. The reaction was allowed to proceed for 4 hours with the jackettemperature so adjusted as to keep the reaction mass at 40 C. Theresulting slurry was illtered, Washed, dried and ball-milled in the samemanner as described under Example 1* with the exception that the washedcrumb was dried for about 16 hours at 60 C.

lunder Example 1 in order to dissolve the copolymer in the aqueouscalcium thiocyanate solution and to obtain a de-aerated solution `,ofcopolyme which would be suitable for spinning.

The amount of copolymer in the above-described spinning solution was 7%,as determined by casting, drying and weighing a. film of the.

cast solution. 'I'he falling ball viscosity of this copolymer solutionat 61 C., as determined by the method described under Example 1, was33.6 seconds.

This solution was spun and stretched to obtain 4an oriented. ber formedof a copolymer of acrylonitrile and methyl acrylate in exactly the samemanner set forth under Example 1 with the exception that the ber wasstretched 900% in the stretch bath.

The bobbin containing the collected, wet, gelled copolymer yarn or berwas suspended in a trough containing an aqueous dispersion of 2%guanylurea 'octadecyl hydrogen sulfate (antistatic agent) and 1% ofN-octadecyl disodium sulfosuccinamate (dispersing agent). Thisdisrsirsign was maintained at a temperature of 40- 17 The treated yarnwas continuously dried, with no accumulation of an electrostatic chargeduring drying, in exactly the same manner described under Example 1 withthe exceptionthat the external surface temperature of the electricallyheated rolls was about 70-75 C. The dried yarn had a denier of 85, afinish content of 2.2%

based on the weight of the dry, untreated yarn,

a dry tensile strength of 4.6 grams per denier, a wet tensile strengthof 4.5 grams per denier, and dry and wet elongations of 12%.

Example 3 A copolymer of acrylonitrile and acrylamide was prepared byrst dissolving 198 parts of acrylonitrile in 2197 parts of water, towhich was added 224.4 parts of a 9.8% aqueous acrylamide solution. Thetemperature of the solution was brought to 38 C. and then 3.5 parts ofsodium metabisulfite was added, followed by 3.5 parts of ammoniumpersulfate. When surrounded by a water bath at 40 C., the temperature ofthe reaction mixture increased during the rst 20 mindescribed above wasdissolved at 45 C. in 85 parts of 55% aqueous sodium thiocyanate toyield a solution having a ball-fall viscosity (as previously described)of 407'seconds at 61 C. After filtering and de-aerating, the soltioncontaining 15% copolymer was extruded through a metal spinneret having100 holes, the diameter of the holes being 55 microns. The solution washeated to reduce the viscosity before extrusion by using a steam-heatedfinger inside the spinneret. Extruding at the rate'of 1.53 grams ofsolution per minute, the fiber was coagulated in water at 5 C. Theextruded ber formed a multilament thread with complete separation of allof the laments. spinneret with 9.5 inches of bath travel to a roller andthence vertically to a godet with a peripheral speed of 1.39 metersperminute. The highly hydrated ber was clear, tough and ductile. Afterwrapping the liber 21/2 times around the aforementioned godet, the berwas carried through 24 inches of bath travel in water at 98 C. andthence to a second godet with a peripheral speed of 18.5 meters perminute around which the ber was wrapped 21/2 times. The peripheral speedof the second godet was 13.3 times that of the rst godet. The stretchedber was wound on a bobbin while still wet, a spray of water beingmaintained on thebobbin to prevent any drying out of the ber.

The bobbin of wet gelled yarn was then suspended in a trough containingan aqueous vdispersion of 1% of guanidine octadecyl hydrogen sulfate(anti-static agent) and 0.5% of butyl stearate (textile lubricant). Thedispersion was maintained at 40-50 C.

The treated yarn was continuously dried, with v no accumulation ofstatic electricity during drying, in exactly thesame manner describedunder Example 1 with the exception that the external surface temperatureof the electrically heated rolls was about 70-75 C.

The ber was drawn from the antenas Ius was wrapped three times.

18 Example 4 To a. solution of 40 C. comprising a mixture of 8774 partsof water, 914 parts of a 9.64% aqueous acrylamide solution and` 792parts of acrylonitrile was added with constant stirring 16 parts ofsodium metabisulfite followed by 16 parts of ammonium persulfate, eachbeing added as a coneentrated aqueous solution. The polymerization wascarried out in a jacketed vessel, and by applying cooling during theearly stage of the polymerization the temperature of the reaction masswas h eld at 40 C. After a total of 2 hours the polymer slurry wasfiltered, and the isolated polymer was washed, dried and ball-milled.One gram of the dry copolymer, dissolved in a aqueous sodium thiocyanatesolution to make 100 ml. at v20 C., had a viscosity at 40 C. of 21.5centiposes.

Seven pmts of the dry copolymer powder was dissolved in 93 parts ofa 50%aqueous calcium thiocyanate solution. After filtering and deaerating,the solution had a viscosity of 18.5 seconds as determined by the timefor a Monel ball, Q-inch in diameter, to fall through 20 centimeters ofthe solution maintained at 61 C.

- The solution was extruded through a 40-hole spinneret with holes of 90microns diameter into water at 3 C. To assist in the extrusion thesolution was heated to about 60 C. inside the spinneret by means of anelectrical heating device such as that briefly described hereinbeforeand more fully in my copending application Serial No. 772,200 withreference to Fig. 2 of the drawing accompanying that application. 'I'hesolution was extruded downwardly at a rate of 6.8 6 grams per minute,and the multil'llament fiber thereby formed was led first to a hook andthence upwardly to submerged rollers so that the total bath travel was21 inches. The fiber was then led to a godet of 50 mm. diameter,hereafter referred to as G-l, around which the liber Thereafter the berwas led to a second godet of 125 min. diameter, hereafter referred to asG2, around which it was wrapped two times. G-l and G-2 both rotated at16 R. P. M., thereby applying a preliminary stretch of 21/2 times to thefiber. From G2 the ber was led through a water bath at 98-99 C. for abath travel of 24 inches and thence to a 94.5 mm. diameter spool whichrotated at 8l R. P. M. The stretch between G-2 and the spool was 3.83times, and the over-all stretch between G-l and the spool was 9.6 times.Y

The spool of wet gelled fiber was then suspended in a. trough containingan aqueous dispersion of 1 part of guanylurea octadecyl hydrogen sulfatein 99 parts of water. This dispersion was maintained at a temperature of40-50 C.

Thetreated yarn was continuously dried, with no accumulation of anelectrostatic charge during dryinain exactly the same manner describedunder Example 1 with the exception that the external surface temperatureof the electrically heated rolls was about -75 C.

It will be understood, of course, by those skilled in the art that, incarrying out the method, I am not limited to the specic polymerizationprod- -ucts and solutions thereof, the specific anti-static agents norto the specific conditions of spinning, stretching, anti-statictreatmentl and drying given by way of illustration in the aboveexamples. Thus, instead of the particular copolymers employed inExamples 2, 3 and 4 I may use any other thermoplastic copolymers of amajor proportion of acrylonitrile and a minor proportion set forth inExamples '2, 3 and 4. Thus, I may use methyl acrylate or acrylamide ascomonoy mers with acrylonitrile in Various other proportions within therange of, by weight, from about 85% to about 97% .of acrylonitrile tofrom'about 15% to about 3% of methyl acrylate or acrylamide, moreparticularly within the range of, by weight, from about 90% to about 95%of acrylonitrile to from about 10% to about 5% of methyl acrylate oracrylamide. Similar ranges of proportions also may be usedadvantageously in many cases with other comonomers, for example suchcomonomers as those mentioned previously herein by way of illustration.

Of the copolymeric acrylonitriles used, I prefer to employ anacrylonitrile copolymer containing in the copolymer molecules an averageof at least about 85% vby weight of combined acrylonitrile. In suchcopolymeric products, the proportions of monomers in thepolymerizable'mixture from which the copolymers are made preferably areadjusted so that the nal copolymer contains in the molecules thereof anaverage of at least about 85% by weight of acrylonitrile (combinedacrylonitrile) The expression acrylonitrile polymerization productcontaining in the molecules thereof an average of at least about 85% byweight of combined acrylonitrile, as used herein, means a polymerizationproduct (polymer, cpolymer of interpolymer or mixture thereof)containing in its molecules an average of at least about 85% by weightof the' acrylonitrile unit, which is considered `to be present in theindividual polymer molecule as the group or, otherwise stated, at leastabout 85% by weight of the reactant substance converted into and formingthe polymerization producty is acrylonitrile (combined acrylonitrile).

Likewise, it will be understood by those skilled in the art that I amnot limited to the specic anti-static agents nor to the specic finishingcompositions containing such an agent that are given in the aboveillustrative examples, since any other anti-static agent or compositioncontaining the same, numerous examples of which have been givenhereinbefore, and which is adapted to obviate or retard materially theaccumulation of static electricity during the continuous drying of thehelices of the Wet, gelled ber as hereinbefore described, may beemployed.

The anti-static agent may be applied to the gelled ber prior to dryingby any suitable means,`

but preferably it is applied in the form of a liquid dispersion, moreparticularly an aqueous dispersion. This dispersion may contain anysuitable amount of anti-static agent, but ordinarily such an agent ispresent in the dispersion in an amount corresponding vto from about 0.5%to about by weight thereof. The dispersion may be applied, for example,by immersing the liber in the dispersion, or by spraying or otherwisecontacting the ber with the dispersion. In applying the dispersion, itis preferably heated to an elevated temperature, e. g., from about 45 or50 to about 95 C., or in some cases even as high as 100 C. With someanti-static agents plied at room temperature (20-30 C.) or attemperatures up to 45 C., but lsuch temperatures may be less desirablewith other anti-static agents because of the greater diiiiculty inmaintaining the anti-static agent homogeneously dispersed in Water orother volatile liquid dispersion medium at the lower temperature. Uponcontinuously drying the treated, gelled ber as hereinbefore described,the dried ber has the anti-static agent deposited at least on the outersurfaces thereof. The amount of anti-static agent which is present in oron the dried, treated ber may vary considerably, but ordinarily it ispresent therein or thereon in an amount, by weight, corresponding tofrom about 0.2% to about 4% of the dried, untreated ber.

The liquid composition containing the antistatic agent may be applied tothe wet, gelled fiber at any suitable stage during its vproduction andprior to continuous drying of the same as hereinbefore described. Aspreviously has been mentioned, it may be applied during the stretchingof the wet spun ber to orient the molecules thereof; orvit may beapplied between any of the guides or godets or other rolls employed inthe spinning process and which'precede the continuous drying of the'wetber. gelled fiber may be dyed, treated withlan antistatic agent, and thewet, dyed ber in gel state then may be continuously dried as previouslyhas been described with particular reference to an undyed, gelled iiber.

If desired, the nishing composition containing the anti-static agentwhich is deposited in or on the treated, dried ber may be allowed toremain in place during and after the production of the article in itsultimate form, especially in those cases wherein the treated ber orfabric or other textile ,or article made from the same is not later tobe dyed. If the dried, treated ber or fabric or other textile or articleproduced from the ber is to be dyed, then the finishing compositioncontainingthe anti-static agent is usually removed therefrom prior todyeing, for example by means of the usual aqueous scouring baths.

The method herein described, and originally claimed in parentapplication Serial No. 68,370, 'providesa rapid and economical means ofcontinuously drying Wet spun,l stretched bers of acrylonitrilepolymerization products, which bers have been produced as disclosed andspecifically claimed in my aforementioned copending application Serialdueto the continuous drying technique employed v and with less threaddamage than when a package-spun, e. g., bobbin or cake, wet thread isdried as a package and later unwound for twisting or rewinding.

Theterm ber as used generically herein is intended to include within itsmeaning both monolaments and multilaments.

I claim:

l. Apparatus for contacting a continuously moving thread with a liquid,said apparatus comprising a vessel having a bottom portion and side andend portions, each of the end portions being provided with an openingadapted for the passage therethrough of the moving thread; a troughlikemember positioned within said vessel, said member being spaced from saidend portions and Walls defining said Itrough-like member being thedispersion containing the same may be approvided with a plurality ofspaced apertures ex- In some cases the tending longitudinally from oneend to the other end of the said member; inlet reservoir means beneathsaid trough-like member; means for introducing a liquid to saidinlet-reservoir means; and means for withdrawing liquid from said vesselafter its passage through the apertures of said trough-like member.

2. Apparatus for contacting a continuously moving thread with a liquid,said apparatus comprising a vessel having a bottom section and verticalside and end sections united to said bottom section, each of the endsections being provided with a slot for the passage therethrough of themoving thread; a trough positioned within said vessel, said trough beingspaced from said end sections and being aligned with the slots therein,at least the bottom portion of the said trough being provided with aplurality of spaced apertures extendingv longitudinally from one end tothe other end thereof; inlet-reservoir means beneath said trough; aconduit for introducing a liquid to said inlet-reservoir means; andmeans for withdrawing liquid from said vessel after its passage throughthe apertures of said trough.

3. Thread-treating apparatus including an appliance for the liquidtreatment of a continuously moving thread, said appliance comprising arectangular vessel having a bottom section and vertical side and endsections joined to said bottom section, each of the end sections beingprovided with a slot for the passage therethrough of the moving thread;a V-shaped trough positioned within said vessel and spaced a suicientdistance from the said end sections as to provide a collecting reservoirat each end of the said trough, the bottom of the said trough beingaligned with the slots in the said end sections, and both the bottomportion and the angular walls forming the sides of the said trough beingprovided with a plurality of spaced apertures extending longitudinallyfrom one end to the other end thereof; inlet-reservoir means beneathsaid V-shaped trough, said means including a portion of the bottomsection of the said rectangular vessel; aconduit for introducing aliquid to said inlet-reservoir means; means extension so as to form acollecting reservoir, and* vertical side andend sections rigidly unitedto said bottom section, each of the end sections being provided with aslot for the passage therethrough of the moving thread; a V-shapedtrough positioned within said vessel and spaced at such distance fromsaid end sections that each end of said trough is substantially invertical alignment with the innermost part of the said recessedextension in said bottom section, the bottom of the said trough beingaligned with the slots in the said end sections, and both the bottomportion and theI angular walls forming the sides of the said troughpeing provided with a plurality of small, spaced apertures extendinglongitudinally from one end to the other end thereof; inletreservoirmeans positioned beneath said V- shaped trough; a conduit forintroducing a liquid to said inlet-reservoir means, said conduit beingconnected to the bottom portion of said inlet reservoir at a point whichis approximately in the center of said bottom portion; conduits forwithdrawing liquid iro-m each of the aforementioned collectingreservoirs after the liquid has passed through the aforesaid apertures;and means for continuously moving the thread to be treated through thesaid appliance.

ARTHUR CRESSWELL.

REFERENCES CITED UNITED STATES PATENTS Name Date Hartmann Feb. 14, 1938Number Certificate of Correction Patent No. 2,558,734 July 3, 1951ARTHUR CRESSWELL It is hereby certied that error appears in the printedspecification of the above numbered patent requiring'correction asfollows:

Column 3, line 18, for patent read parent; column 4, line 54, forproducts read product; line 64, for ca-licum read calcium; column 14,line 62, for metabisulde read metabz'sulfite; column 15, line 43, forposition read positioned; column 16, line 11, for 1.8 read 2.8; column18, line 2, for solution of read solution at; column 20, line 7, fortemperature read temperatures; column 21, line 2, for inlet reservoirread nZet-1'eservoi/r; column 22,1ne 23, for peing read bei/ng;

and that the said Letters Patent should be read as corrected above, sothat the same may conform to the record of the case in the Patent Oiice.

Signed and sealed this 12th day of February, A. D. 1952.

THOMAS F. MURPHY,

Assistant Commissioner of Patents.

